Limestone is a sedimentary rocks that are formed at the bottom of lakes and seas and mainly consists of Calcite carbonate; CaCO³. As a slit and organic matter settle to the bottom. More and more layers build up over thousands and millions of years, and adding more and more weight, and by the influence of heat and pressure cause chemical reactions It has a smooth granular surface, does not show much graining or crystalline structure and varies in hardness. Some dense limestones can be polished. The common colors are Blue, Grey, Black, Brown and Green.